Another guy making custom 3D printed axle housing (lots of large pictures)

[T_Tank]

I'm always impressed at the strength of the parts shapeways makes. I've got a midnight pumkin sized tlt-1 monster truck with 3d printed upper 4link/servo mounts on the axle an they handled some very violent crashes on a 1/10 buggy track going at the speeds at or past 30 then hitting the double! Cleared the double but boy she did not settle when landing XD

Now the question is at the size which is close to a mini lst if the 3d printed chassis can survive crashes exceeding 25mph with a 540.

If it can survive go fast hopefully it can survive go slow an pulling stumps!

[onecool54@yahoo]

Have you given any thought to the size of hardware that has to be used on the axle. The one thing about the mini axles I don't care for are the small rod ends. It sucks to have to go out and buy a whole bunch of new 2.5mm nuts and bolts for a build. Looking forward to the axles being available.

[T_Tank]

Plan with the axles will be they will have the default holes for the stock mrc ends but will have enough material that you can use a drill to widen the link holes to accept normal 3mm traxxas end links.

As for the screws to assemble the axles they use stock mrc sized scews used on the normal axle.


Here is a progress of working on the mmt chassis lots of head scratching going on an thinking what might fail under a crashing situation.



Reason for the upper link offset is to keep a triangulation around 44 degrees for the upper link minimum. The body reference is a very poof attempt at the stock mini lst body hope I eyeballed and measured right before I attempt the cage for the cab

[T_Tank]

A bit more progress don't look forward to designing the battery box >.<

also need to figure out a good compact esc that can handle a 4000k 9.5t turnigy trackstar motor as that's the sanest spare I have (other is a 4.5t viper vstXL 550!)

Receiver I'm looking at is the spektrum sr300wp which will fit mostly in the front little tray area with the connectors dangling downward.

Haven't done the cab section yet I dont' know if parma's mini lst body has the cab in about the same area as the stock mini lst body.
anywho less talk here's a pic!


Shock mounts will come in eventually as I adhd my way around this chassis

[T_Tank]

bit of a hefty update on the chassis the cage section is now removable so it can tilt up to access the battery and esc (not shown in picture)

Uses mini lst body posts and allows them to slide up an down like the stock units

Notched the receiver tray to in hope keep the antenna wire from getting pinched int he nose



Still need to make the battery box and esc tray.... anyone want to give me some good common esc options for a 540 and 380 motor?
I've looked at the mamba max micro, mamba max water proof, novak edge 2s, novak gtb2

Fun fact on the motor mount its the same width and bolt pattern as the stock mrc plate so... you don't HAVE to run a 540 in this!

And i'm sure this sounds like a bad idea but dual mamba max micros with dual 0808 4000kv motors on a mini lst trans and gear it to the moon?

[T_Tank]

A couple of updates to post for everyone to check out

Made a battery box for the mini monster truck chassis that accepts standard losi 1/18 lipo and nimh packs.



Now here is the update on the axles with the 2nd revision everything fits correctly though is a smidge on the tight side but I"m sure that if I adjusted the bearing seats more they end up loose now an then on prints.







Gotta go by hobby bench monday and grab a set of mrc end links for the upper 4 link mounts but the axles are a direct drop in even the rear axle lock out slips right on with all the holes aligned!

[MRCrackhead]

This build is awesome.

Ground up design, very cool.

[T_Tank]

Thanks sure is not easy and progress might not be the fastest but I'll try to keep them comin

[T_Tank]

Been a long time coming but finally able to get most of the chassis this month with the exception of the battery box wich will need to be redesigned.
Posting from my tablet so i'm putting links up instead of direct images as they may be a bit big.

sideshot with half the chassis in showing you can use the vxl mount with a stock chassis plate so.. in theory you can use a vxl trans in any stock style after market chassis
http://i928.photobucket.com/albums/a...psrfbunezb.jpg

front shot with a side by side comparison next to a slick rock cage (would need to make a lower inner chassis to use a vxl in a slick rock to much stuff in the way)
http://i928.photobucket.com/albums/a...psg1ua4zyl.jpg

Huston we have a roller! mind you a cobbled together one but goal was to be able to use stock or custom axles with it and I need to dig out some thicker traxxas wheel hexes and a few traxxas links to get the alingment more... consistant

http://i928.photobucket.com/albums/a...ps4ufbu1ii.jpg

http://i928.photobucket.com/albums/a...psmovll5bl.jpg

http://i928.photobucket.com/albums/a...psgsrqedvn.jpg

and finally a couple of shots of the truck with a mini lst body sitting on top!
http://i928.photobucket.com/albums/a...psw5psv5ol.jpg

http://i928.photobucket.com/albums/a...psomrqb8sn.jpg

now for the little bit of bad news.. after getting everything.. I am gonna need to rethink how to power this thing as there is really no way to fit the battery size I wanted.. any ideas what could fit that be high enough C rating to fuel a 540 4000kv motor?

Then I miss measured the thickness of the metal part of the 540 mount so I can do two things
1) make a varient of the chassis mount that moved the whole trans forward 8mm for clearance of the rear axle better an keep a healthy pinion angle
2)raise the trans (rather avoid this keep the cog lower..)

Also... can't find my fourth stock mrc shock... and lower ball ends for those teeny things.. guess gotta buy a couple rebuild kits and a shock body set. Though if anyone has a old set of stockers just collecting dust send me a pm!

Anyways sorry for such a long delay its really been killing me that I havent been able to further work on this over the past year makes me so happy to see this starting to take shape in front of me!

[T_Tank]

Minor progress update going to try out some aluminum reinforcing in the duratraxx vendatta statalite gears to see if I can keep thise truck from having locked axles.

Ring an pinion seam to not care about being beaten up by a 17.5t motor with a 32t Pinion 55t spur with vxl trans in overdrive and axle running in OVERDRIVE aswell!!!! wonder if I can find a smaller vxl spur like a 35t an run a 38t pinion for MORE overdrive!!!

[89redranger]

Project is coming along nicely! When I have some more free time I'll shoot you a PM. Till then, I'm watching!

[T_Tank]

look forward to hearing from ya!

Now I ran into a surprise the other day at srs driving the truck around the track going up the first jump that fallows a tripple (no way was I trying to clear it all just went about foot an a half air born off the ramp) and landing.... the right axle tube snapped off right at the diff case >.<.

Chassis is fine surprisingly but seeing how the axle snapped looking at redesigning the axle.. maybe even add in ounting for a axle truss while still compatible with mrc servo/link mounts.

Thoughts anyone?

edit

Well folks already threw together a new design concept v3 of the axles still can flip the ring gear but the whole thing I feel is a lot beefier ironically this variant is cheaper to print an most of the link mounts are stock location so they be a direct drag an drop

[89redranger]

Lookin good! You thought at all about moving the shock mounts to the top of the axle, and outboard? Maybe integrate the chubs into the housing, and locate the shock mounts just inboard the king pin location?

[T_Tank]

The thought has crossed my mind but first thing I'd like to do is make a housing thats a direct drop in for folks that have stock mrc with a 4 link conversion already. Maybe on the modular version I'll add a way to screw mounts to either top/back/bottom ends of the axle just have to think about how strong those would be. I snapped my v2 housing going about 25mph off a 3ft tall jump though none of the link/shock mounts broke.

[T_Tank]

So here are few pics of the truck with the mrc an mini T trans just so you can see what kind of room the truck has with those trans options.

First up mrc! with novak three80 motor attached

Did run the truck around with this was about... 10-15mph guess good for a rookie class mt race








And the mini T trans (had binding issues in it.. need to figure that out)

Complete madness with such a low ratio in the trans but need pin style grub screws for the outdrives keep pushing them out of the plastic traxxas universals so unable to really get a idea of top speed but likely.. close to the merv trans or faster.





didn't take a further back side pic with the mini t trans as it sits at the same hieght as the mrc.

Good lord though these trans options make the truck unbelievably light! That... might actually be a problem XD

[89redranger]

10-15 mph would still be way more than necessary for "scale" MT freestyle and race runs. The appeal and fascination with Mini MTs for me has always been the small area needed to run them. Anywho, rig is looking awesome. Still watching.

[T_Tank]

I guess you would be right with the lower speed an lighter weight of the trans/motor be easier to get a bunch of these and hold mini races.

With the top mounted shock option would folks like to have the option to do dual should shocks on each axle?

Still beating up the chassis with the heavier 540 vxl configuration so far only one area I can see needs to be changed for structural reasons. Second thing I need to change is the shock mount location to have them further out for more tuning options I made them to close when figuring the stock body I'm using

edit

Going to look at making a 3 link bar like the stock mrc's so folks could just swap their mrc chassis for the mmt chassis an then be able to later on upgrade to 4link. Note the 3 link would be incompatible with the vxl trans and I doubt I could get the 3D print accuracy right enough a socket in the custom axle housings

speaking of axles here is a render of the modular link mount variant of the axle with a top shock mount on the axle. woulda made it modular but not sure how well it would survive crashes an such not much room for extra hardware trying to keep it simple



edit as of 2/8/2016
Ordered revision 3 none modular variant of the new axle design should be in by the 19th or 20th hopefully. Also did the minor revision to the chassis the shock mounts are now a bit more forward by about... 12mm each so the shocks can be at a better angle.

Really would like some feedback folks good bad or ugly!

[T_Tank]

New axle came in the mail only issue I have is the thin tabs for the link mounts need about .25mm more material around the holes so they don't risk cracking when screwed in otherwise everything fits like a glove (pinion bearings need to be "coaxed" into fitting with a ballpeen)

now for pictures






Mounted up!







So what ya folks think?

[89redranger]

One word...proper!

Looks very scale to a real MT axle. You're missing the planetary hubs, but they would be fragile, pointless, heavy, and overly complicated at this scale.

[T_Tank]

Thanks man!
Yeah I'm loving how they came out! I'm waiting on parts to repair the diffs again after blowing the stock mrc locker out with the merv configuration then its taking the truck out an beating on that rear axle an seeing how it holds up might even put it up front to see how it handles those stresses.

Could always make some faux planetary hubs.

For that matter I could make a version that has all the link mounts built in for even more scale appeal but then I'd need to figure out where to put the servo as most monster trucks do not have panhard steering an use hydraulics so I guess I'd have to hide some small MG wing servos behind the axle on either side of the input shaft